1. Field of the Invention
The present invention relates to a so-called coated-type magnetic recording medium in which a magnetic layer or the like is coated on a nonmagnetic base film.
2. Description of the Related Art
A so-called coated-type magnetic recording medium in which a magnetic layer or the like is coated on a nonmagnetic base film is generally formed by coating a magnetic coating formed of magnetic powders, a binding agent, an organic solvent and other additive on the nonmagnetic base film made of poly(ethylene terephthalate) or the like to dry it.
At this time, in order to especially secure an output of a video signal band and a C/N ratio thereof, a film thickness of the magnetic layer is controlled and a smooth base film having a center-line mean roughness Ra smaller than 8.0 nm is employed.
However, if a thickness of a coated film is reduced in order to reduce costs of a coating material and so on, then a ground of the base film influences a property of a surface of the magnetic recording medium, which lowers the output and the C/N ratio.
In order to solve this problem, it can be considered that a more smooth base film is used and more minute-particle magnetic powders are used. However, if the base film is made more smooth, then the manufacturing costs therefor are increased, which is a bar to reduce the costs of the materials and so on. If the more minute particle magnetic powders are used, it is difficult to disperse the particles in a solvent of the magnetic coating and there are then the problems that the coated magnetic powders are peeled off from the base film and that head clogging characteristics are lowered.